Drysdallite
A valid IMA mineral species
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About Drysdallite
Alan R. Drysdall
Formula:
MoSe2
Colour:
Grayish black with a brown tint
Lustre:
Metallic
Hardness:
2
Specific Gravity:
6.248 (Calculated)
Crystal System:
Hexagonal
Member of:
Name:
Named in honor of Alan Roy Drysdall (23 May 1933, Southampton, England - 11 January 2017, Southampton, England) geologist and Director of the Geological Survey of Zambia. The cynodont Luangwa drysdalli is also named for him.
Unique Identifiers
Mindat ID:
1322
Long-form identifier:
mindat:1:1:1322:8
IMA Classification of Drysdallite
Approved
IMA Formula:
Mo4+Se2-2
Approval year:
1973
First published:
1973
Classification of Drysdallite
2.EA.30
2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)
E : Metal Sulfides, M: S <= 1:2
A : M:S = 1:2 - With Cu, Ag, Au
2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)
E : Metal Sulfides, M: S <= 1:2
A : M:S = 1:2 - With Cu, Ag, Au
2.12.10.2
2 : SULFIDES
12 : AmBnXp, with (m+n):p = 1:2
2 : SULFIDES
12 : AmBnXp, with (m+n):p = 1:2
3.8.9
3 : Sulphides, Selenides, Tellurides, Arsenides and Bismuthides (except the arsenides, antimonides and bismuthides of Cu, Ag and Au, which are included in Section 1)
8 : Sulphides etc. of Cr, Mo, W an Mn
3 : Sulphides, Selenides, Tellurides, Arsenides and Bismuthides (except the arsenides, antimonides and bismuthides of Cu, Ag and Au, which are included in Section 1)
8 : Sulphides etc. of Cr, Mo, W an Mn
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Dry | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Pronunciation of Drysdallite
Pronunciation:
| Play | Recorded by | Country |
|---|---|---|
| Jolyon Ralph | United Kingdom |
Physical Properties of Drysdallite
Metallic
Transparency:
Opaque
Colour:
Grayish black with a brown tint
Streak:
Brownish black
Hardness:
2 on Mohs scale
Hardness:
VHN7=46 - 58 kg/mm2 - Vickers
Tenacity:
Waxy
Cleavage:
Perfect
on {0001}
on {0001}
Comment:
Pliable, difficult to pulverise
Density:
6.248 g/cm3 (Calculated)
Optical Data of Drysdallite
Anisotropism:
Very strong, light bluish gray to purplish brown
Reflectivity:
| Wavelength | R1 (%) | R2 (%) |
|---|---|---|
| 400nm | 17.0% | 38.0% |
| 420nm | 18.2% | 37.8% |
| 440nm | 19.4% | 37.6% |
| 460nm | 20.4% | 37.6% |
| 480nm | 21.4% | 37.5% |
| 500nm | 21.8% | 37.5% |
| 520nm | 21.8% | 37.4% |
| 540nm | 21.6% | 37.1% |
| 560nm | 21.4% | 36.7% |
| 580nm | 21.1% | 36.0% |
| 600nm | 20.8% | 35.5% |
| 620nm | 20.6% | 35.1% |
| 640nm | 20.5% | 35.0% |
| 660nm | 20.4% | 35.0% |
| 680nm | 20.4% | 35.2% |
| 700nm | 20.4% | 35.6% |
Graph shows reflectance levels at different wavelengths (in nm). Peak reflectance is 38.0%.
R1 shown in black, R2 shown in red
Pleochroism:
Strong
Comments:
White to very light gray, to pinkish gray
Chemistry of Drysdallite
Mindat Formula:
MoSe2
Elements listed:
Crystallography of Drysdallite
Crystal System:
Hexagonal
Class (H-M):
6/mmm(6/m2/m2/m) - Dihexagonal Dipyramidal
Space Group:
P63/mmc
Setting:
P63/mmc
Cell Parameters:
a = 3.287(1) Å, c = 12.925(2) Å
Ratio:
a:c = 1 : 3.932
Unit Cell V:
120.94 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Steep pyramidal crystals, massive
Comment:
Space group from synthetic material
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 2.373 Å | (100) |
| 6.46 Å | (75) |
| 2.845 Å | (55) |
| 1.913 Å | (55) |
| 1.643 Å | (40) |
| 1.615 Å | (40) |
| 2.153 Å | (25) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| High-? alteration and/or metamorphism | |
| 33 : Minerals deposited by hydrothermal metal-rich fluids (see also [#12]) |
Type Occurrence of Drysdallite
Place of Conservation of Type Material:
Charles University, Prague, Czech Republic, number 17348.
National School of Mines, Paris, France, number 50743.
National Museum of Natural History, Washington, D.C., USA, number 145627.
National School of Mines, Paris, France, number 50743.
National Museum of Natural History, Washington, D.C., USA, number 145627.
Geological Setting of Type Material:
Oxidation zone of uranium deposit
Associated Minerals at Type Locality:
Synonyms of Drysdallite
Other Language Names for Drysdallite
Relationship of Drysdallite to other Species
Member of:
Other Members of Molybdenite Group:
| Molybdenite | MoS2 | Hex. 6/mmm(6/m2/m2/m) : P63/mmc |
| Tungstenite | WS2 | Trig. 3m : R3m |
Related Minerals - Strunz-mindat Grouping
| 2.EA. | Radvaniceite | GeS2 |
| 2.EA. | Zavyalovite | Ag2TeS3 |
| 2.EA.05 | Sylvanite | AgAuTe4 |
| 2.EA.10 | Calaverite | AuTe2 |
| 2.EA.15 | Kostovite | CuAuTe4 |
| 2.EA.15 | Krennerite | Au3AgTe8 |
| 2.EA.20 | Melonite | NiTe2 |
| 2.EA.20 | Merenskyite | PdTe2 |
| 2.EA.20 | Ognitite | NiBiTe |
| 2.EA.20 | Shuangfengite | IrTe2 |
| 2.EA.20 | Berndtite | SnS2 |
| 2.EA.20 | Sudovikovite | PtSe2 |
| 2.EA.20 | Kitkaite | NiTeSe |
| 2.EA.20 | Moncheite | Pt(Te,Bi)2 |
| 2.EA.25 | Verbeekite | PdSe2 |
| 2.EA.30 | Jordisite | MoS2 |
| 2.EA.30 | Molybdenite | MoS2 |
| 2.EA.30 | Tungstenite | WS2 |
| 2.EA.40 | Pampaloite | AuSbTe |
Other Information
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Drysdallite
mindat.org URL:
https://www.mindat.org/min-1322.html
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References for Drysdallite
Localities for Drysdallite
Showing 2 localities.
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
All localities listed without proper references should be considered as questionable.
China | |
| Linbo Yao et al. (2001) |
Zambia (TL) | |
| Cech et al. (1973) +1 other reference |
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Kapijimpanga, Solwezi District, North-Western Province, Zambia